Combined tire pressure monitoring and keyless entry receiver

0001The present application is a continuation in part of U.S. patent application Ser. No. 10/079,665 filed Feb. 20, 2002 that claims priority to U.S. Provisional Patent Application Ser. Nos. 60/276,210 filed Mar. 15, 2001; 60/269,959 filed Feb. 20, 2001; 60/276,325 filed Mar. 16, 2001; 60/298,258 Jun. 14, 2001; 60/290,923 filed May 15, 2001, 60/352,489; filed on Jan. 23, 2002, and 60/349,882 filed Jan. 17, 2002.

BACKGROUND OF THE INVENTION

0002This invention relates to a receiver assembly for receiving transmissions of varying formats and specifically to a receiver assembly for receiving both amplitude shift keyed signals and frequency shift keyed signals.

0003Conventional methods of monitoring tire pressure include positioning a sensor within each wheel to monitor pressure. The sensor assembly typically emits a radio frequency (RF) transmission indicative of tire conditions. A receiver disposed within the vehicle receives the RF signal and actuates a messages or warning light to signal the operator of tire conditions.

0004Many motor vehicles include a remote keyless entry system including a key fob carried by an operator to actuate door locks or other features. The remote keyless entry system includes a receiver disposed within the motor vehicle to receive transmissions from the key fob and actuate vehicle systems in response to transmissions received from the key fob. It is known in some systems to utilize the same type of transmission for the tire monitoring system as is used in remote keyless entry system.

0005Typically, a transmission is modulated as either an amplitude shift keyed ASK, or a frequency shift keyed FSK radio frequency. The ASK transmission modulation is best suited for applications in which the receiver and transmitter are relative stationary to each other. In addition ASK transmissions are favorable when there exists a relatively long distance between the transmitter and the receiver. However, an ASK transmission becomes disrupted when the receiver or transmitter is moving relative to one another. The FSK signal is suited for transmitters that are moving relative to the receiver because the amplitude remains essentially constant for the duration of any transmission. However, the FSK transmission has lower peak field strength than a comparable ASK transmission. The FSK transmission is specifically suited for use with the sensor assembly disposed within the tire and the ASK is suited for use with the remote keyless entry system.

0006Accordingly, it is desirable to develop a receiver capable of receiving both ASK and FSK transmissions to optimize the capabilities of both the tire monitoring system and the remote keyless entry system.

SUMMARY OF THE INVENTION

0007An embodiment of this invention is a receiver assembly including an amplitude key shifted mode and a frequency shift mode for receiving transmissions from different systems within a motor vehicle.

0008The receiver of this invention receives signals from a tire pressure monitoring system and the remote keyless entry system. The receiver assembly forwards data received from each system to a vehicle controller. The vehicle controller processes data for the tire pressure monitoring system to indicate tire conditions or the remote keyless entry system to actuate unlocking of doors or other such functions as are known to a worker skilled in the art.

0009The receiver assembly comprises an Amplitude Shift Keyed mode (ASK) and a Frequency Shift Keyed mode (FSK). The FSK mode receives signals from the sensor assemblies of the tire pressure monitoring system. The ASK mode receives signals from a key fob for the remote keyless entry system to initiate locking or unlocking of doors.

0010The receiver receives first and second signals, each in different formats. Each signal is configured for the specific application of data transmission. ASK transmissions are favorable for situations where the transmitter and receiver are substantially stationary. The ASK radio frequency transmission is easily disrupted by abrupt changes in received field strength and therefore are not favorable sending transmission from a moving object such as the tires of a motor vehicle. However, the ASK provides greater signal power which is desirable for the remote keyless entry system of this invention. The ASK transmission allows for higher peak output field strength, relative to a comparable FSK transmission. However, the ASK transmission decreases typical battery life and is therefore not desirable for applications such as tire condition sensing that require longer battery life due to the difficulty of changing batteries of the sensor assemblies disposed within the tire of the motor vehicle.

0011The FSK signal is favorable for conditions were the transmitter or receiver is moving during data transmission. As appreciated, rotation of a tire will introduce amplitude variations in the transmission caused by changes in received field strength. If the sensor assembly data was transmitted by way of an ASK transmission, the noise caused by rotation of the tire would cause data in the transmission to become corrupted. However, an FSK transmission is amplified upon receipt to effectively remove any amplitude disturbances. Further, the FSK transmission is less power intensive and therefore more adaptable to the sensor assembly application that requires longer battery life.

0012The receiver assembly includes the ASK mode and the FSK mode providing one receiver for both the remote keyless entry system and the tire monitoring system. Sensor assemblies of the tire pressure monitoring system transmit a signal emitted that includes an ASK wakeup pattern, an identity code and a data signal. The signal is a FSK transmission, except for the ASK wake up pattern that precedes the signal.

0013The wake up pattern precedes the signal to indicate that subsequent signals sent to the receiver will be in FSK format. Once a first wake up pattern is received from the signal and wake up pattern are repeated to ensure that the receiver accurately receives data. If the data signal is sent more than once, subsequent signals do not require the wake up pattern. The wake up pattern is used only before a series of signal repeats or bursts.

0014The receiver assembly defaults to the ASK mode. In the ASK mode the receiver operates at a lower power and is therefore the default mode that is on when the receiver assembly is activated. The ASK wake up signal alerts the receiver assembly to incoming FSK transmission, which causes the receiver assembly to switches to FSK mode. The switch between ASK and FSK mode provides use of a signal receiver for gathering data from several different motor vehicle systems using differing data signal formats.

0015The system of this invention includes a receiver capable of receiving both ASK and FSK transmissions providing a single receiver capable of receiving data from more than one system with the motor vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

0016The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:

0017<figref idref="DRAWINGS">FIG. 1</figref> is a schematic view of a motor vehicle including a tire monitoring and remote keyless entry system;

0018<figref idref="DRAWINGS">FIG. 2</figref> is a schematic view of the receiver assembly

0019<figref idref="DRAWINGS">FIG. 3</figref> is a graph comparing field strength over time of an ASK signal

0020<figref idref="DRAWINGS">FIG. 4</figref> is a graph comparing field strength over time for an FSK signal

0021<figref idref="DRAWINGS">FIG. 5</figref> is a schematic representation of a signal sent to the receiver from a motor vehicle system; and

0022<figref idref="DRAWINGS">FIG. 6</figref> is a schematic representation of a wake up pattern; and

0023<figref idref="DRAWINGS">FIG. 7</figref> is a schematic view of a data signal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

0024An embodiment of this invention is a receiver <b>16</b> for receiving data from more than one system of a motor vehicle <b>10</b> shown schematically in FIG. <b>1</b>. One system is a tire pressure monitoring system <b>26</b> including sensor assemblies <b>14</b> disposed within each of four tires <b>12</b> along with an additional tire <b>12</b> carried as a spare. The sensor assemblies <b>14</b> gather data indicative of conditions within each tire <b>12</b> and transmit data signals to the receiver assembly <b>16</b>. The motor vehicle <b>10</b> also includes a remote keyless entry system <b>20</b> for locking and unlocking doors of the motor vehicle <b>10</b>. The receiver <b>16</b> of this invention can also receive signals from other systems disposed within the motor vehicle <b>10</b> as are known to a worker skilled in the art. The tire pressure monitoring system <b>26</b> and the remote keyless entry system <b>20</b> are discussed as examples of how the receiver <b>16</b> of this invention operates to receive data from more than one system of the motor vehicle <b>10</b>.

0025The receiver assembly <b>16</b> forwards data received from each of the systems <b>20</b>, <b>26</b> to a vehicle controller <b>18</b>. The vehicle controller <b>18</b> processes data for the tire pressure monitoring system <b>26</b> to indicate tire conditions or the remote keyless entry system <b>20</b> to actuate unlocking of doors <b>24</b> or other such functions as are known to a worker skilled in the art. Preferably the remote keyless entry system <b>20</b> is an active system requiring actuation, such as by depressing buttons on a key fob <b>22</b>, however, it is within the contemplation of this invention for passive remote keyless entry system that do not require a positive action by the operator.

0026The receiver assembly <b>16</b> of this system is also used with the remote keyless entry system <b>20</b>. The receiver assembly <b>16</b> is configured to receive transmission from both the sensor assemblies <b>14</b> and the key fob <b>22</b>. Although a key fob <b>22</b> is specifically described, it is within the contemplation of this invention that the remote keyless entry system <b>20</b> includes other active or passive transmitting means to initiate entry or operation of the motor vehicle <b>10</b>.

0027The tire pressure monitoring system <b>26</b> receives data from the sensor assemblies <b>14</b> through the receiver <b>16</b> and controller <b>18</b>. The controller <b>18</b> in turn coordinates display of information indicative of current tire conditions to an operator of the motor vehicle <b>10</b>. The specific configuration of the tire pressure monitor system <b>26</b> can be of any type known to a worker skilled in the art. Further, it is within the contemplation of this invention that the receiver <b>16</b> can receive data from other systems disposed within the motor vehicle known to a worker skilled in the art.

0028Referring to <figref idref="DRAWINGS">FIGS. 1 and 2</figref>, the receiver assembly <b>16</b> comprises an Amplitude Shift Keyed mode (ASK) <b>52</b> and a Frequency Shift Keyed mode (FSK) <b>58</b>. The FSK mode <b>58</b> receives signals from the sensor assemblies <b>14</b>. The ASK mode receives signals from a key fob <b>22</b> for the remote keyless entry system <b>20</b> to initiate locking or unlocking of doors <b>24</b>. The receiver assembly <b>16</b> also includes an antenna <b>48</b> to receive transmissions from the key fob <b>22</b> and the sensor assemblies <b>14</b>. The receiver assembly <b>16</b> includes a low frequency driver <b>50</b> to emit a signal to the sensor assemblies <b>14</b> to initiate transmission by the sensor assemblies <b>14</b>.

0029The antenna <b>48</b> is preferably of a length one quarter that of the wavelength of the transmission received. Transmission received by the antenna <b>48</b> proceed through resistor <b>54</b> to the RF receiver <b>16</b>. A controller <b>60</b> controls which of the <b>58</b> and <b>52</b> are engaged to receiver incoming transmission.

0030The receiver <b>16</b> receives first and second signals, each in different formats. Each signal is configured for the specific application of data transmission. ASK transmissions are favorable for situations where the transmitter and receiver are substantially stationary. The ASK radio frequency transmission is easily disrupted by abrupt changes in received field strength and therefore are not favorable sending transmission from a moving object such as the tires <b>12</b> of a motor vehicle <b>10</b>. Referring to <figref idref="DRAWINGS">FIG. 3</figref>, the received field strength <b>62</b> of an ASK signal <b>64</b> is shown for an application where the receiver and transmitter move relative to each other. The changes in the received field strength <b>62</b> change for any number or reasons within a motor vehicle including interference created by other onboard systems and the specific environment present at the time of the signal. However, the ASK signal provides greater signal power which is desirable for the remote keyless entry system of this invention. The ASK signal allows for higher peak output field strength, relative to a comparable FSK signal. However, the ASK signal decreases typical battery life and is therefore not desirable for applications such as tire condition sensing that require longer battery life due to the difficulty of changing batteries of the sensor assemblies disposed within the tire of the motor vehicle.

0031Referring to <figref idref="DRAWINGS">FIG. 4</figref>, an FSK signal <b>68</b> is favorable for conditions were the transmitter or receiver is moving during data transmission. As appreciated, rotation of a tire will introduce amplitude variations in the transmission caused by changes in received field strength <b>66</b>. If the sensor assembly <b>14</b> data was transmitted by way of an ASK signal, the noise caused by rotation of the tire would cause data in the transmission to become corrupted. However, an FSK signal is amplified upon receipt to effectively remove any amplitude disturbances. Further, the FSK signal is less power intensive and therefore more adaptable to the sensor assembly application that requires longer battery life.

0032Referring to <figref idref="DRAWINGS">FIGS. 2 and 5</figref>, the receiver assembly <b>16</b> is shown schematically and includes ASK mode <b>52</b> and FSK mode <b>58</b>. This configuration allows the receiver assembly <b>16</b> to be used for both the remote keyless entry system <b>20</b> and the tire monitoring system. Sensor assemblies <b>14</b> of the tire pressure monitoring system <b>26</b> transmit a signal <b>28</b> emitted that includes an ASK wakeup pattern <b>30</b>, an identity code <b>32</b> and a data signal <b>34</b>. The signal <b>28</b> is a FSK transmission, except for the ASK wake up pattern <b>30</b> that precedes the signal <b>28</b>.

0033<figref idref="DRAWINGS">FIGS. 5-7</figref> schematically illustrate the content of the signal <b>28</b> transmitted from sensor assembly <b>14</b> to the receiver <b>16</b>. Preferably, the signal includes 96 bits that is transmitted at 9600 baud or 10 milliseconds per data frame. Note that it is within the contemplation of this invention that the signals comprise varying bit lengths and transmission rates according to application specific parameters. The signal <b>28</b> illustrated is from the sensor assembly <b>14</b> of the tire pressure monitoring system <b>26</b> and is an example of one type of signal within the scope and contemplation of this invention.

0034The wake up pattern <b>30</b> precedes the single <b>28</b>. The wake up pattern <b>30</b> is 50 ms in duration and includes a portion <b>70</b> that indicates that subsequent signals sent to the receiver <b>16</b> will be in FSK format. The portion <b>70</b> preferably comprises 5 bytes. Each byte includes information according to each specific application that initiates activation of the FSK mode <b>58</b>. Further, once a first wake up pattern <b>30</b> is received from the signal <b>28</b> and wake up pattern <b>30</b> are repeated to ensure that the receiver <b>16</b> accurately receives data. If the data signal is sent more than once, subsequent signals <b>28</b> do not require the wake up pattern <b>30</b>. The wake up pattern <b>30</b> is used only before a series of signal repeats or bursts.

0035Referring to <figref idref="DRAWINGS">FIG. 7</figref>, the single <b>28</b> includes a preamble portion <b>44</b> of 15 bits and a start portion <b>46</b> of 1 bit that initializes the signal <b>28</b> with the receiver <b>16</b>. Identification portion <b>32</b> includes 32 bits of information that includes the identification information necessary to correlate the information received from each sensor assembly <b>14</b> with specific vehicle parameters. Byte <b>7</b> indicated at <b>33</b> provides information on battery status and the time delay to the next frame of data. The time delay provides for interleaving of signals from various sensors to prevent signal collisions. Further, byte <b>7</b>, indicated at <b>33</b> provides a wheel unit state.

0036The wheel unit state is an indication of conditions within the specific tire <b>12</b>. The wheel unit state indicated at <b>12</b> includes fast and slow pressure changes with the motor vehicle <b>10</b> in part, normal driving and test mode, transmissions due to fast pressure or temperature changes and low frequency detection driving and test mode. Note that the conditions are only some of the possible wheel conditions that can be indicated by signal and it is within the contemplation of this invention that other conditions as known by a worker in the art may be used.

0037The signal <b>28</b> also includes the data indicated at <b>36</b>, <b>38</b> and <b>40</b> for the specific tire. The byte indicated at <b>36</b> is indicative of pressure within the tire. The byte indicated at <b>38</b> is indicative of temperature within the tire and the byte indicated at <b>40</b> is indicative of acceleration of the tire. Further, bytes comprising the signal include a “checksum”, indicated at <b>41</b> along with byte <b>42</b> that provides data indicative of the frame number, software version, and end of message (EOM). Note that although the contents of the data signal <b>28</b> are described in detail, it is within the contemplation of this invention that the data signal <b>28</b> may comprise any data depending on application specific requirements, as would be known to a worker skilled in the art.

0038Referring to <figref idref="DRAWINGS">FIG. 2</figref>, the receiver assembly <b>16</b> defaults to the ASK mode <b>52</b>. The receiver <b>16</b> in ASK mode <b>52</b> operates at a lower power and is therefore the default receiver that is on when the receiver assembly <b>16</b> is activated. The receiver <b>16</b> will switch over to the FSK mode <b>58</b> in response to a triggering event. Preferably the triggering event is receipt of the wake up signal <b>30</b>, however, other triggering events such as motor vehicle speed or acceleration are also within the contemplation of this invention. The conditions of the motor vehicle <b>10</b> traveling above the desired speed or in a parked position provide definite indicators for the switch between FSK and ASK modes <b>58</b>, <b>52</b>. However, when the vehicle <b>10</b> is idling, for instance in a traffic jam, but not moving at the desired speed to switch from the ASK mode <b>52</b> and the FSK mode <b>58</b> the system will not switch over to the FSK mode <b>58</b> unless another conditions are satisfied.

0039Each signal <b>28</b> is preceded by the ASK wake up pattern <b>30</b> that is sent before the FSK signal. The ASK wake up pattern <b>30</b> alerts the receiver assembly <b>16</b> to incoming FSK transmission, which causes the receiver assembly <b>16</b> to switch over to the FSK mode <b>58</b>. The switch between ASK and FSK modes <b>58</b>,<b>52</b> provides use of a signal receiver <b>16</b> for gathering data from several different motor vehicle systems using differing data signal formats. Therefore, providing for the optimal data signal to be used for each system of the motor vehicle <b>10</b>.

0040The foregoing description is exemplary and not just a material specification. The invention has been described in an illustrative manner, and should be understood that the terminology used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications are within the scope of this invention. It is understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.